Dynamical angular correlation in molecular Auger decay

Area of Science:

• Molecular physics
• Atomic and molecular collisions
• Quantum chemistry

Background:

• Understanding molecular photoionization dynamics is crucial for chemical reaction mechanisms.
• Auger electron spectroscopy provides insights into electronic structure and decay pathways.
• Fixed-in-space molecular targets allow for detailed studies of angular correlations.

Purpose of the Study:

• To measure the angular distribution of Auger electrons emitted from fixed-in-space CO molecules.
• To investigate the influence of molecular orientation and ionization channels on Auger electron spectra.
• To explore the interplay between photoionization and Auger decay processes.

Main Methods:

• Experimental measurement of Auger electron angular distributions using fixed-in-space molecular beam technique.
• Targeted ionization of the C K-shell in CO molecules using synchrotron radiation.
• Analysis of spectral variations with respect to light polarization and molecular axis orientation.

Main Results:

• First measurements of Auger electron angular distributions from fixed-in-space CO molecules.
• Observed dramatic spectral variations in the CO(2+)B(1)Sigma Auger final state.
• Demonstrated dependence of angular distributions on initial ionization channels (Sigma or Pi) and photon energy.

Conclusions:

• The observed spectral variations indicate a strong dynamical angular correlation between photoionization and Auger decay.
• Results challenge the validity of a simple two-step model where these processes are treated independently.
• Highlights the need for more sophisticated models to describe molecular Auger decay following photoionization.